Putative filariosis outbreak in white and black rhinoceros at Meru National Park in Kenya

BACKGROUND: Habitat and food supply loss and disruption, together with man’s pursuit of the animal’s unique horn pose significant threats to the charismatic rhinoceros. Filarial worms have been thought to cause cutaneous lesions in black rhinoceros (Diceros bicornis) in Kenya and South Africa, but never in white rhinoceros (Ceratotherium simum) in the wild, despite the fact that the two species live often in close proximity. Stephanofilaria dinniki has been implicated in the past as the causal agents for such lesions. FINDINGS: In this paper we report a putative filariosis outbreak in both black and white rhinos at Meru National Park in Kenya. Four black and five white rhinos were affected by various degrees of filarioid-like lesions, while apparently all sympatric wild and domestic animals were filarial worm-free. Affected rhinos were captured and successfully treated. Comparison between the epidemiological aspects of white and black rhinoceros filariosis, and the possible relations between this outbreak and annual seasons, the presence of oxpeckers and other host species are discussed. CONCLUSIONS: Our study highlights (i) that filarial infection is not restricted to black rhinos, but it affects both rhinoceros species, and (ii) the importance of the earlier detection and immediate treatment (capture-treat and release) of filarioid infections, which is of pivotal interest for wildlife conservation, and especially the endangered and isolated white and black rhinoceros populations.